Posted: April 13, 2010

How Nanoparticles penetrate thin layers of fullerenes

(Nanowerk News) Physicists discover an important mechanism for the decomposition of nano-composites – published in Nature Nanotechnology ("The Ouroborand: A Cavitand with a Coordination-Driven Switching Device").
A cooperation of researchers at the Universities of Freiburg and Dortmund as well as the Freiburg Fraunhofer Institute for Mechanics of Materials has succeeded in placing an article in the recent issue of the renowned Nature Nanotechnology journal. The article reviews their findings concerning the properties of smallest metal nanoparticles.
The physicists have put the particles onto a layer of globular C60-carbon molecules and discovered that those can permeate a one-layered film at room temperature, but not a second layer. Based on those findings, the contact ability of metal nanoparticles could be deliberately modulated through different thicknesses of the films.
Properties of nanoparticles often differ from the larger pieces of the same materials. By chosing size and composition of the nanoparticles, chemical, optical or magnetic properties can be “custom-tailored” in a way that is impossible for solid state materials. However, in order to realise these promising possibilities of the nanoparticles in chemical catalysis, magnetic storage technology or optoelectronics, the particles need to be fixed onto surfaced or matrices. In doing so, interactions between nanoparticles and the surface might occur, which could even destroy the particles’ special characteristics. Thus, the development of techniques that fix particles “gently” but safely was targeted. The researchers have now come up with a possibility to fix nanoparticles onto a surface without changing their geometric structure, and, most notably, they have characterised the decay process of nanoparticles under certain circumstances.
They were able to demonstrate that the double layer of fullerenes on a metal surface constitutes an optimal substrate for the fixation of nanoparticles. This way, the particles kept their shape and size even at room temperature for several days. Brought onto a single fullerene-layer however, the particles quickly shrinked and disappeared within hours. Due to these findings, the stability of nanoparticles can be understood much better, which is a prerequisite for the development of technical applications of custom-tailored nano-systems.
Source: University Freiburg